1. Field of the Invention
This invention relates to modified polystyrene polymers and is more particularly concerned with phospholene-substituted polystyrenes and with processes for their preparation and processes for their use as catalysts for converting isocyanates to carbodiimides.
2. Description of the Prior Art
It is known that certain phospholene oxides are catalysts for the conversion of isocyanates to carbodiimides; see U.S. Pat. No. 2,853,473. It has also recently been disclosed (see German Offenlegenschrift No. 2,504,334; published after the present invention was made) that certain phospholane-phosphonic acid salts of amino-modified polystyrenes can be employed as catalysts for the same reaction.
We have now found that certain phospholene-substituted polystyrenes are highly effective catalysts for the conversion of organic isocyanates to the corresponding carbodiimides and are possessed of marked advantages when employed for this purpose.